Abstract: A Mathematicalmodel was developed to simulate soil water infiltration from a buried trickle source. The model was solved numerically by an approach of the noniterative ADI difference procedure. And variable boundaries were used for saving computing time. The numerical results were compared with field test. The comparisons indicated that the method is reliable. Typical results showed the effect of trickle discharge, irrigation volume and buried depth of dripper on soil moisture content and the wetted pattern. Some suggestions were presented by the numerical results for design and management of sub-surface trickle irrigation.